1. Field of the Invention
This invention relates to a lens barrel for a camera.
2. Description of the Prior Art
In cameras of the through-the-lens or TTL metering type, each interchangeable lens is provided with an interlocking pawl for transmitting the open F-value and/or the preset aperture value of the lens to the metering circuit in the camera. This interlocking pawl is designed to be connectible to an exposure interlocking pin provided in the viewfinder when the lens barrel has been mounted to the camera, thereby enabling interchange of the viewfinder containing the metering circuit. An aperture scale is also formed adjacent to the interlocking pawl so that it may be observed extraneously of the camera.
In new cameras permitting the use of such a lens barrel, for example, cameras of the type in which the interlocking pawl is not used to transmit the lens-side information, such as preset aperture value, to the camera side, but in which the information is transmitted to the metering circuit by a different type of interlocking mechanism or other means, the preset aperture value which is seen on the lens barrel is introduced directly into the viewfinder through the display optical system. However, where the interlocking pawl is not eliminated, by taking into account the interchangeability of the lens barrel with conventional cameras, the very presence of the interlocking pawl has made it difficult to introduce the aperture scale for extraneous observation into the viewfinder.